Low mass presser mechanism for sewing machines



July 17, 1962 A. N. HALE ETAL 3,044,428

LOW MASS PRESSER MECHANISM FOR SEWING MACHINES Filed Dec. 28, 1959 2Sheets-Sheet 1 FIG. I.

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A. N. HALE J. N. COVERT R. W. VOLKMANN INVENTORS BY wmw ATTORNEYS July17, 1962 A. N. HALE ETAL LOW MASS PRESSER MECHANISM FOR SEWING MACHINES2 Sheets-Sheet 2 Filed Dec.

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A. N. HALE J. N. COVERT R. W. VOLKMANN INVENTORS ATTORNEYS United StatesPatent Ofi ice dfiddfizd Patented July 17, 1962 The specification whichfollows relates to improvements in a presser foot for high speed sewingmachines. It meets the prOblems presented by increase in the speed ofsewing machines and difficulties arising from new synthetic fabrics.

In the trend toward obtaining ever greater speeds in Sewing machines, ithas been considered necessary to apply increasing pressure to thepresser foot in order to feed the work properly. However, in machines ofhigh speeds, where insufliciently pressure is supplied to the presserfoot, it has a tendency to break contact with the feed dog on impact andagain at the point where the dog begins its downward motion, in otherwords, the inertia of the presser foot is too great to allow it tofollow the feed dog at high speed.

One result of this failure of the presser foot'to follow closely thework feeding motion of the feed dog is that less feed contact resultsbetween the feed dog and the foot and thereby the length of the stitchis reduced. This condition is caused by the inertia of the aggregatemass of the presser foot, presser bar, strike-off wire, the strikeoffwire holder and other related parts moved by the feed dog. The greaterthe mass, the greater must be the pressure applied to the parts in orderto overcome their inertia. The inertia is directly proportional to themass of the parts which have to be moved.

In order to have the presser foot more closely follow the verticalmovements of the feed dog at high speeds a material increase in pressureon the presser bar is neces sary. However, such increase in pressure hascaused several adverse side effects; such as, producing puckered seams,uneven ply feeding, and the breaking of the thread chain betweengarments.

Improvement was made by redesigning the presser bar parts of lighterweight. However, with the advent of presentday fabrics of the Wash andwear type, there is still a well defined tendency to pucker even withthe use of less pressure afforded by the use of presser bar parts oflight weight. To overcome this difliculty, the present invention hasbeen developed in the direction of mini mixing the mass of the movingparts at high speed and effecting close response to the movements of thefeed dog.

One of the main objects of the invention is to provide a presser foot,the presser bottom of which will closely follow the movements of thefeed dog but will not transfer such feed dog movement to the presser barand its related parts, as is ordinarily the case in the usual sewingmachine.

Another object of the invention is to restrict the movement to thepresser foot bottom only against a spring mounted on the presser foot.

A further object of the invention is to utilize a spring havingunrestrained movement which will not cause wear on the pivot arm orlink.

Among the objects of the invention is to apply spring pressure to thepresser foot bottom in a direction approximately perpendicular to theplane through which the fabric is being fed.

A still further object of the invention is to provide an extremely fineadjustment under the spring.

Incidental to the novel adjustment of the spring is a self-lockingfixture.

It will also be noted that by the design of a foot bottom mounting, itis prevented from any side play.

The purposes of this invention have been carried out by providing apresser foot carrying a forked bracket with a hinged link from which thefoot bottom is pivoted and applying spring power to the line vertically,so that there need to be movement only by the foot bottom and the linkthus capable of following the movements of the feed dog with greatrapidity.

The preferred form of this invention has been illustrated by way ofexample on the accompanying drawings in which:

FIGURE 1 is a side elevation of a sewing machine on which the novelpresser foot has been mounted;

FIGURE 2 is a front elevation of the improved presser foot;

FIGURE 3 is a perspective view of the slide and operating spring;

FIGURE 4 is an enlarged side elevation;

FIGURE 5 is a rear elevation of a modified form and FIGURE 6 is aperspective view of the separated parts of the link, slide and footbottom of the modified form. r

On the drawings there is shown a presser bar 7 which forms a mountingfor the presser foot 8 in the usual manner. The presser bar is adjustedin such a manner that it will apply no, or at least very little pressureto the presser foot. The presser foot 8 has a laterally extendingbracket 9. This is in the form of a bifurcated fork having spacedparallel side plates it), 10. s

These side plates have two pairs of aligned holes 11. A link 12 iscarried by' a pivot pin 13 in one pair of the holes. 1 Y

A stop pin 14 is mounted in one pair of holes provided above each of thepairs of holes 11.

A foot bottom 15 is pivoted to the forward end of the link 12 betweenflanges 16 which fit loosely outside of the link 12. This insures thatthe foot bottom will be restricted to vertical oscillation free fromlateral displacement.

A diagonal arm 17 is mounted upon the bracket 9. This arm carries ascrew-threaded stud l8 firmly attached by means of a locknut 19. Thestud 18 is provided with a knurled nut 2d which may be 'adjustablythreaded on the stud.

Resilient means for holding the link 12 and the foot bottom 15 down isprovided by a wire spring 21. This spring has an upper loop 22 which, asshown in FIGURE 1, passes around the stud 18 and the sleeve ofthe'adjusting nut 20. i

At an intermediate point the spring 21 is provided with a pair ofopposite loops 23. These loops are held by a hinge screw 24 passingbetween the side plates 10,10 of the bracket.

A shoe plate, 25 rests upon the upper surface of the link link 12 andshoe 25 are smooth so that sliding movement will be possible whenlubricated and in a condition of minimum friction.

The top surface of the shoe 2 5 has a' transverse groove 26. e s

The lower ends of the spring 21 are turnedinwardly at right angles asshown at 27 and fitted within the transverse groove 26.

Adjusted tension of the spring 21 is exerted upon the shoe plate 25 in adirection approximately perpendicular to the plane in which the fabricis fed by the feed dog 28. In the present instance this is exertedvertically. The feed dog lifts the shoe bottom 15 in high speedmovements.

a sence If thepresser foot is lifted, such aswhen it is necessary tolift the presser foot for insertion of the fabric, the link 12 comes incontact with the stop pin 14 and thus prevents the bottom 15 fromdropping beyond thedesired point.

There is an appropriate freedom of movement between the shoe plate 25and the top surface of the link 12. This is practically withoutfriction. Should a rather heavy seam present itself to the presser footit will cause the shoe plate to move forward on the link a greateramount than that normally due to the usual feed motion because of thegreater lifting movement to the presser foot as it goes over the seam. Yj V In the modification shown in FIGURES and 6, the novel tension uponthe link 29 is transmitted to a cornpensating presser foot of the typedisclosed in United States Letters Patent 2,288,051."

In this instance the link has parallel depending flanges 30, 31. Abottom member 32 is provided with an,

upstanding block 33. This block is held inside the flange 30 by means ofa transverse pin 34. Thus the block 33' fits closely against the innerside of the flange 3d and slightly spaced'from the lower surface of thelink 29, so that the member 32 can move relative to the link 29 only ina pivotal movement.

A second bottom member 35 is fitted against the inner side of the flange31. The member 35 .has two spaced lugs 36, 36. The lugs 36, 36 overhangthe side of the 7 member 32, which thus prevents the member 35 fromdropping out of position.

The lugs 36, 36 have recesses in the top each containing a coil spring37 which is under tension against the bot-. tom surface of the link 29.Thus the bottom member 35 may move vertically with respect to the member32.

The pressure of the feed dog 23 against the undersides of members 32,35, is thus transmitted to the link 29. The pressure is there exertedagainst the shoe plate 25 as above described.

In theabove mounting of the foot bottom it will be observed that innormal operation at high speed, the movement caused by the action of thefeed dog will be transmitted through the link 12 or 29 as the case maybe,

against the tensioned shoe plate 25. Here the vertical movement isabsorbed by the resilience of spring 21 without transmitting forceagainstthe presser bar 7. There is thus no possibility of a bindingcondition between sliding members. Also, the mass which must be moved bythe feed dog is limited to that of the presser foot-bob a self-lockingfeature. I The essential features of the invention having been described and illustrated in the preferred form by way of example, permitvariation in minor details of material and proportions without departingfrom the scope of the invention as defined in the following claims.

What we claim is: a 1. A presser mechanism for sewing machinescomprising a presser bar, a presser foot attached thereto, a forkedbracket on the presser foot, a'link pivoted to the bracket, a footbottom pivoted to the outer end of the link, and resilient means hingedon the presser foot and having a free end pressing downwardly on thelink 'in front of its pivot with the bracket.

2. A presser mechanism for sewing machines comprising a presser bar,apress'er foot attached thereto, a

forked bracket on the presser foot, a link, a pin for the linkselectively pivoted on the bracket, a stop pin selectively carried bythe bracket in the path of the link, a foot bottom pivoted to the outerend of the link, and resilient means hinged on'the presser foot andhaving a free end pressing downwardly on the link in front of its pivotwith the bracket.

3. A presser mechanism for sewing machines comprising a presser bar, apresser foot attached thereto, a forked bracket on the presser foot, alink pivoted to the bracket, a foot bottom pivoted to the outer end ofthe link, a shoe plate slidably resting on the link and resilient meanshinged on the bracket and having a free end presslog downwardly on theshoe plate.

A 4. A presser mechanism for sewing machines comprising a presser bar, apresser foot attached thereto, a forked bracket on the presser foot, alink-pivoted to the bracket, a toot bottom pivoted to the outer end ofthe link, a shoe plate slidable .on the link, a spring pivotally mountedin said bracket with one end resting on said shoe plate and adjustablemeans on the bracket for applying tension to the opposite end of' thespring.

"5. A presser mechanism for sewing machines com prising a presser bar, apresser foot attached thereto, a

' forked bracket on the presser foot, a link pivoted to the bracket, afoot bottom pivoted to the outer end of the link, a shoe plate slidableon the link and an arm on the on the bracket, a rearwardly extendingscrew mounted on the arm, a nut adjustably carried on the screw, aspring loop pivotally mounted in said bracket with one end resting onsaid shoe plate-and the opposite end extending upwardly with its loopedend around the screw in frontof the nut.

7. A presser mechanism for sewing machines comprising a presserbar, apresser foot attached thereto, a forked bracket on the presser foot, alink pivoted to the bracket, parallel depending flanges on the link, afoot bottom pivoted to the outer end of the link, an upstanding block onthe bottom between said flanges and resilient means hinged on thepresser foot and having a free end pressing downwardly on said link infront of its pivot with the bracket.

8. A presser mechanism for sewing machines comprising a presser bar, apresser foot attached thereto, a

forked bracket on the presser foot, a link pivotally attached at one endto said bracket, a presser foot bottom attached tothe other end of saidlink, resilient means hinged intermediate its ends to said presser footwith its front end bearing down on the said link and means carried bysaid bracket to apply tension to the opposite end of said resilientmeans.

References Cited the file of this patent UNITED STATES PATENTS 963,135Gatchell July 5, 1910 1,339,121 Moffatt May 4, 1920 1,921,277 Wolf Aug.8, 1933 1,943,203 Chudner Jan. 9, 1934 2,419,494 Knau's Apr. 22, 19472,730,979 Bell Jan. 17, 1956

